# RECALIBRATE p_win — HOLDOUT REPORT (measure-only; NOTHING DEPLOYED)
2026-07-31. p_win not flipped live, no grade rebuilt, no calibrator shipped.
Per PART A doctrine: MLB and WNBA are treated as SEPARATE MODELS throughout —
fit separately, selected separately, judged separately, and they reach opposite
verdicts. No global instrument was fitted.

## METHOD
Time-forward split PER SPORT (earlier half fits, later half proves — never the
same rows). Both instruments fitted on TRAIN only: single-parameter **Platt**
(`p_cal = sigmoid(a + b·logit p)`, a/b from a weighted fit of TRAIN bucket
empirical-logit on bucket mean-logit) and **isotonic-with-pooling** (TRAIN bucket
rate applied to HOLDOUT by bucket, min 8 per bucket). Inputs: `p_win` + `outcome`
only — no market field, no closing value, no lookahead.

## ⚠️ A MEASUREMENT CORRECTION I MADE MID-RUN
My first pass reported `mean|p − outcome|` (~0.46–0.51). **That is not
calibration** — it is individual-level error on 0/1 outcomes, dominated by
irreducible noise, and it would have made every instrument look identical and
useless. Reliability is only meaningful **on buckets**: bucket mean *predicted*
vs bucket *actual rate*, n-weighted — the same metric T0 used. All numbers below
are the corrected, bucketed metric.

## RESULTS ON HOLDOUT

**Reliability** (n-weighted |predicted − actual| across holdout buckets; lower better)

| sport | holdout n | buckets | raw | Platt | isotonic |
|---|---|---|---|---|---|
| **MLB** | 119 | 4 | 0.1038 | 0.1120 | **0.0939** |
| **WNBA** | 93 | 3 | 0.1322 | **0.0491** | 0.0667 |

**Resolution** (does the ordering survive? Pearson r with outcome, holdout)

| sport | raw | Platt | isotonic |
|---|---|---|---|
| **MLB** | 0.1388 | 0.1284 | **0.1225** |
| **WNBA** | −0.1201 | +0.1269 | +0.0322 |

Fitted Platt parameters: **MLB a=−0.381, b=+0.705** · **WNBA a=+0.040, b=−0.081**.

---

# VERDICT — MLB: QUALIFIES, MODESTLY. INSTRUMENT = ISOTONIC.

**Selected by holdout, not assumed** (the order was right to forbid assuming
Platt): isotonic **0.0939** beats raw 0.1038 and beats Platt 0.1120 — Platt made
MLB *worse*.

- **(a) Reliability: improves.** 0.1038 → 0.0939, ~10% relative. **Real but
  modest** — this does not make an 84%-that-hits-65% into a truthful forecast; it
  shaves the exaggeration.
- **(b) Resolution: SURVIVES.** 0.1388 → 0.1225. Slightly lower (expected — a
  monotone map preserves rank; the Pearson dip is the non-linearity), and
  critically **it is not crushed to zero**. High p_win still hits more than low.
- Both (a) and (b) hold → **MLB qualifies to be graded** in a later, separately
  gated order.

# 🔴 VERDICT — WNBA: ABSTAINS. ITS PLATT "WIN" IS A FAKE WIN.

WNBA's Platt reliability (0.0491) is the best number in this report **and must be
rejected**, exactly per Mandate 3.

**Why it is fake:** the fitted slope is **b = −0.081 — NEGATIVE and near zero**.
So `sigmoid(0.040 − 0.081·logit p)` is **nearly constant at ≈0.51 for every
input**. It "calibrates" by **discarding the prediction and emitting the base
rate**. That is precisely the failure Mandate 3 pre-registered: *"a model
calibrated by crushing everything to the base rate has NO resolution → FAKE win
→ reject."*

The apparent resolution improvement (−0.120 → +0.127) is the **sign flip**, not
skill: a negative slope inverts the ordering, so the model would be serving the
opposite of its own forecast — fitted on **n≈96** of anti-signal. Isotonic tells
the same story more quietly (resolution collapses to **+0.032**, i.e. no
ordering).

**WNBA cannot be made honest AND predictive on this data. It abstains.** Per
Mandate 4 that is two models — one ready, one not — not one model half-working.

---

# THE HONEST CEILING, STATED PLAINLY
MLB's forecast can be made *less* dishonest and keeps its (modest) ordering:
holdout resolution ≈ **0.12**, reliability ≈ **0.094** on **n=119**. That is a
usable-but-unimpressive forecaster, not a sharp one. WNBA has no honest forecast
at all today.

**Cautions carried forward:** holdout n is 119/93 with only 4 and 3 usable
buckets — enough to reject WNBA and to prefer isotonic for MLB, **not** enough to
certify a letter ladder. And the T0 pathology is only *reduced*, not cured: the
top MLB buckets remain the thinnest and the most exaggerated.

**Nothing about market edge, CLV, or beating the close appears in any pass/fail
line above** — as the order required. The instruments were judged only on whether
the forecast tells the truth and still ranks.

## TAGS
VERIFIED: per-sport time-forward holdout results; isotonic beats Platt and raw on
MLB; WNBA's Platt win is a base-rate collapse with a negative slope.
CANNOT DETERMINE: per-archetype calibration (Mandate 3d) — bucket n falls below
the reporting floor once split by sport AND archetype on 442 rows.
**DEPLOYED: NOTHING.** Queries committed at `scripts/pwin-calibration-holdout.sql`.